An alarm system in present use is usually provided with a remote monitor panel, where the sensor illuminates a signal light and activates an audio alarm. The switch at the monitor panel will deactivate the signal and the warning is lost. The need for a simple circuit to deactivate the audio means, and retain the visible signal until manually disconnected at the sensor location is obvious, particularly in the case of stationary engines where a warning of excessive heat, and the like, requires assurance that the attendant has remedied the trouble before the unit is completely deactivated.